Excessive woofer cone excursion is when the cone extends forward or backward beyond it's intended mechanical motion limit. I've experienced that in my subwoofer, and it's very audible when it occurs. Almost sounds like a hard object is hitting a softer one, and the cone is going to pop. Similar to your car's suspension bottoming out when you hit a dip in the road, not a pleasant thing. It never happens when I'm playing music, only on movies with excessive LFE.
In your case, using two Bryston 7B-STs might be a bit of overkill, but not in the negative way you think. They're probably more power than you need, but I think what will end up happening is that you'll never tax the amps, so you'll always get clean amplification feeding your Paradigms. I think your Studio 100s are rated for amps up to 350 watts, and 210 watts maximum input. You might find that the Bryston 4B-ST at 250 watts per channel is all the amp you'll need.
In your case, using two Bryston 7B-STs might be a bit of overkill, but not in the negative way you think. They're probably more power than you need, but I think what will end up happening is that you'll never tax the amps, so you'll always get clean amplification feeding your Paradigms. I think your Studio 100s are rated for amps up to 350 watts, and 210 watts maximum input. You might find that the Bryston 4B-ST at 250 watts per channel is all the amp you'll need.